Re: why are there [v e c t o r s] in Lisp?

[Pascal J. Bourguignon]

Emanuel Berg <embe8573@student.uu.se> writes:

> "Pascal J. Bourguignon" <pjb@informatimago.com>
> writes:
>
>>> Why the syntax is there at all is to provide fast
>>> (faster) access to the vector data type which has
>>> other time and space properties than do lists.
>>
>> ABSOLUTELY NOT.
>>
>> For example, in C++ you have vectors and lists, but
>> you don't have any literal syntax for them.
>>
>> You can have fast and slow data structures without
>> having any literal syntax for it.
>>
>> Why do you keep confusing the two concepts?
>
> The original question was why there is a special
> syntax for vectors, even as lists are perfectly fitted
> to be vectors.

You did it again.  You are asking why apples are of a certain color,
even as peaches have a kernel.

The two things are totally unrelated.


> The question was not why there are lists AND vectors.

If the question excludes this, then then original question is "why there
is a special syntax for vectors?".  And I gave you the answer: because
otherwise you would have to build vectors are run-time using a more
complex expression and a more complex algorithm.  Also, the compiler
couldn't perform the optimization it is allowed to perform on literal
objects, namely coalescing of equal literals, and storing them in ROM.


> But that issue is also interesting so that discussion
> wasn't wasted on anyone who read it (perhaps).
>
> As for the syntax, the "literal"
>
>     [1 2 3]
>
> is a faster and more readable way than
>
>     (vector 1 2 3)
>
> to tell the computer when it should use what, because
> the computer isn't advanced enough to figure this out
> on it own.

I don't know what you mean by "this" in "figure this out on its own".

The speed is irrelevant here, there are semantic differences:

(setf print-circle t)
(loop repeat 3 collect [1 2 3])        --> (#1=[1 2 3] #1# #1#)
(loop repeat 3 collect (vector 1 2 3)) --> ([1 2 3] [1 2 3] [1 2 3])


-- 
__Pascal Bourguignon__                 http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
keep the man from touching the equipment.” -- Carl Bass CEO Autodesk